Why don't you join Masham as a Grayling member to start with, it gets your foot in the door, a few guys on here did just that,

not quite sure who is next stretch up from Masham but just slightly upstream the black bull club have the fishing downstream of Kilgrim Bridge, Thornaby have upstream of Kilgrim Bridge and Jerveaux Fly Fishers also have the opposite bank right up near enough to Middleham, Downstream from Masham that belongs to Tanfield which you wont get in to unless you have loads of £££££, sorry cant be more specific but its a starter